In the present application, the investigators propose further studies with the overall objective of assessing the hypothesis that ring-opened metabolites play a role in benzene hematotoxicity. The specific aims of the proposal first are to perform toxicity studies to further assess the hematologic toxicity of reactive ring-opened metabolites by synthesizing four additional compounds and comparing their effects with those of MUC and benzene. The four new compounds are the mixed aldehyde carboxylic acid derivative, (MUC-COOH); the as yet unidentified MUC-Y derivative; cis, cis-muconaldehyde; and, cis,trans-muconaldehyde. Secondly, metabolism studies will be performed for determine whether MUC is formed from benzene in bone marrow microsomes in vitro, and in comparison with liver microsomes; and to further investigate the metabolism of MUC in liver fractions, including the identification of "MUC-Y". Finally, the investigators will conduct adduct studies to assess the formation of macromolecular adducts of MUC in vivo with the aim of both providing an assay of MUC formation and of providing information about the toxicity of MUC using benzene and MUC-treated animals.